1. Field of the Invention
The present invention relates generally to a Precision Approach Control (PAC) system for stabilizing an aircraft during landing thereof, such as during a relatively precise landing on an aircraft carrier, and more particularly pertains to a precision approach control system which provides the pilot with precise control over the rate of change of the flight path angle of the aircraft during landing. The precision approach control system also maintains the aircraft at a predetermined angle of attack during landing.
2. Discussion of the Prior Art
Precise control of the flight path of an aircraft should be maintained throughout a landing approach to an aircraft carrier, which makes this a very demanding task for a pilot. During such a landing, the pilot is presented with a relatively narrow landing window along an ideal glide slope path. The landing is further complicated by uncertain aircraft carrier motions and also by atmospheric and ship-induced turbulences.
The landing approach of high-performance, relatively unstable aircraft on an aircraft carrier is an even more demanding task, requiring precision control of the flight path by the pilot. The prior art has used Stability Augmentation Systems (SAS), Approach Power Compensators (APC), and Direct Lift Control (DLC) subsystems to augment the basic aircraft flying qualities and control systems, but using separate design criteria for each of these different subsystems. With the main objectives of these subsystems (short period response, phugoid damping, g control) achieved, the pilot is given improved control over the aircraft. However, in high-performance, relatively unstable aircraft requiring exceptional flight path control, this design methodology is generally insufficient since it does not assure precise flight path control.
However, none of the prior art approaches has resulted in an entirely satisfactory solution to the problem of providing a pilot with precise flight path control over an aircraft during a relatively critical landing thereof such as on an aircraft carrier.
Manual and Automatic Carrier Landing (ACL) designs resulting from an integrated approach to the flight path control problem, as well as the application of qualitative flight path control criteria, have achieved superior flight path response in a Grumman F-14 aircraft with minor modifications to its existing hardware, which has been demonstrated in studies and piloted simulations.